Potential Role and Clinical Value of PPP2CA in Hepatocellular Carcinoma.

BACKGROUND AND AIMS: Protein phosphatase 2A (PP2A) is associated with many cancers. This study aimed to clarify whether PPP2CA, which encodes the alpha isoform of the catalytic subunit of PP2A, plays a role in hepatocellular carcinoma (HCC) and to identify the potential underlying molecular pathways. METHODS: Based on bioinformatics, public databases and our in-house RNA-Seq database, we analyzed the clinical value and molecular mechanism of PPP2CA in HCC. RESULTS: Data were analyzed from 2,545 patients with HCC and 1,993 controls without HCC indexed in The Cancer Genome Atlas database, the Gene Expression Omnibus database and our in-house RNA-Seq database. PPP2CA expression was significantly higher in HCC tissue than in non-cancerous tissues (standardized mean difference: 0.69, 95% confidence interval [CI]: 0.50-0.89). PPP2CA expression was able to differentiate HCC from non-HCC, with an area under the summary receiver operator characteristic curve of 0.79 (95% CI: 0.75-0.83). Immunohistochemistry of tissue sections confirmed that PPP2CA protein was up-regulated in HCC tissues. High PPP2CA expression in HCC patients was associated with shorter overall, progression-free and disease-free survival. Potential molecular pathways through which PPP2CA may be involved in HCC were determined using miRWalk 2.0 as well as analysis of Gene Ontology categories, Kyoto Encyclopedia of Genes and Genomes pathways, and protein-protein interaction networks. CONCLUSIONS: PPP2CA is up-regulated in HCC and higher expression correlates with worse prognosis. PPP2CA shows potential as a diagnostic marker for HCC. Future studies should examine whether PPP2CA contributes to HCC through the candidate microRNAs, pathways and hub genes identified in this study.

Taurine improves the spatial learning and memory ability impaired by sub-chronic manganese exposure.

BACKGROUND: Excessive manganese exposure induced cognitive deficit. Several lines of evidence have demonstrated that taurine improves cognitive impairment induced by numerous neurotoxins. However, the role of taurine on manganese-induced damages in learning and memory is still elusive. This goal of this study was to investigate the beneficial effect of taurine on learning and memory capacity impairment by manganese exposure in an animal model. RESULTS: The escape latency in the Morris Water Maze test was significantly longer in the rats injected with manganese than that in the rats received both taurine and manganese. Similarly, the probe trial showed that the annulus crossings were significantly greater in the taurine plus manganese treated rats than those in the manganese-treated rats. However, the blood level of manganese was not altered by the taurine treatment. Interestingly, the exposure of manganese led to a significant increase in the acetylcholinesterase activity and an evidently decrease in the choline acetyltransferase activity, which were partially restored by the addition of taurine. Additionally, we identified 9 differentially expressed proteins between the rat hippocampus treated by manganese and the control or the manganese plus taurine in the proteomic analysis using the 2-dimensional gel electrophoresis followed by the tandem mass spectrometry (MS/MS). Most of these proteins play a role in energy metabolism, oxidative stress, inflammation, and neuron synapse. CONCLUSIONS: In summary, taurine restores the activity of AChE and ChAT, which are critical for the regulation of acetylcholine. We have identified seven differentially expressed proteins specifically induced by manganese and two proteins induced by taurine from the rat hippocampus. Our results support that taurine improves the impaired learning and memory ability caused by excessive exposure of manganese.

[Study on differential display genes of tolerant-damage of MRC-5 induced by formaldehyde of low dose].

OBJECTIVE: To observe the differentially expressed genes of the human embryo lung fibroblast (MRC-5) induced by formaldehyde (FA) of low dose using fluoro DD-PCR. METHODS: The dose-effect relation of FA toxicity to MRC-5 was acquired, No observed damage effect or proliferation concentration was used as low dose, and obvious damage concentration was used as high dose. MRC-5 was treated with low and high dose, and treated with high dose after pretreated with low dose for some time. Then Fluoro differential display polymerase chain reaction (Fluoro DD-PCR) was used to search differentially expressed genes of the differently treated groups of FA. 61 differential display straps were acquired and 11 of them were reamplified, cloned, sequenced and blasted. RESULTS: According to the dose-effect relation of FA toxicity to MRC-5, 100 micromol/L was choosed as low dose and 10 mmol/L was choosed as high dose. Samples of differently treated groups were amplified by means of fluro-DD-PCR, 61 differentially expressed straps were acquired. 11 differential display straps have been cloned, sequenced and blasted. Two of them were known genes: one was highly homologous to nuclear factor of activated T-cells 5 (NFAT5) and the other was highly homologous to tetratricopeptide repeat domain 3(TPRD-3). Nine of them were new genes. CONCLUSION: It seemed that FA of low dose could promote MRC-5 proliferation and find 61 differentially expressed genes of differently treated groups, and the result of clone could provide scientific base for mechanism of FA toxicity research.

[Adaptive response induced by low concentration of hydroquinone in human embryonic fibroblasts cells].

OBJECTIVE: To study the adaptive response induced by hydroquinone(HQ) on eukaryocyte and its possible mechanism. METHODS: After hydroquinone treatment, AlamarBlue reduce rate, LDH release rate were observed to determine the cell proliferation and death. Annexin V/propidium iodide (PI) staining was performed for each treatment to distinguish viable, early, and late apoptosis or dead cells. The total cellular proteins were separated using two- dimensional gel electrophoresis and visualized by sliver staining. Digital images were analyzed using ImageMaster 2D platinum 5.0 software. The differentially expressed protein spots were picked and digested in gel then identified by tandem mass spectrum. RESULTS: The results of AlamarBlue reduce rate, LDH leakage and Annexin V-FITC/PI staining showed that no effect on cell viability was observed at a concentration of 10 micromol/L HQ while 250 micromol/L HQ significantly decreased cell viability. Cells pretreated with 10 micromol/L HQ for 12h show increasing survival to the following expose to 250 micromol/L HQ. In control MRC-5 cells 1429 +/- 369 protein spots were detected and, 1453 +/- 307 in low HQ group, 1191 +/- 393 in high HQ group, and 1107 +/- 247 in adaptive group by two dimensional gel electrophoresis. Twenty-four protein spots showed significant change after HQ stimulation and 22 protein spots were identified by tandems mass spectra. These identified proteins involved in energy metabolism, translation and RNA processing, protein folding, redox regulation, cell structure and cell signaling. CONCLUSION: Adaptive response can be induced by low concentration of HQ on MRC-5 cells and cellular adaptation is a complex process involving in a modulation of diverse cellular functions.

[Two-dimensional electrophoresis and mass spectrometry analysis on effects of trichloroethylene on protein of L-02 liver cells].

OBJECTIVE: To study the effects of trichloroethylene (TCE) on the protein in L-02 cells in vitro. METHODS: Thiazolyl blue and Trypan blue tests were used to investigate the cytotoxicity of TCE to L-02 liver cell. The 2-D electrophoresis was used to analyse the expression of proteins in L-02 liver cells. The differentially expressed protein spots were identified by matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-TOF-MS). RESULTS: When the concentration of TCE exceeded 30 micromol/L, there was distinct cytotoxicity to L-02 cell (P < 0.05). Selected 40 micromol/L to treat L-02 liver cells and analyze the differential proteome expression, the results showed that the expression level of 37 protein spots was up-regulated and 15 protein spots was down-regulated. And 15 proteins were identified by MALDI-TOF-TOF-MS. CONCLUSION: TCE can change the proteome expression of L-02 liver cell. It should provide the fundamental information to identify proteins related to TCE in further study.

[Study on differential proteomic expression in human liver cells stimulated by trichloroethylene with proteomics].

OBJECTIVE: To explore the differential proteomic expression in human liver cells L-02 induced by different dosages of trichloroethylene (TCE). METHODS: Human liver cells L-02 were treated with different concentrations of TCE and the solvent control (dimethylsulfoxide). The total cellular proteins were separated using 2DE and visualized with silver staining after TCE treatment. The images were analyzed with Image Master 2D Platinum 5.0 analysis software. The differentially expressed protein spots were identified by matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-TOF-MS). RESULTS: Fifteen protein spots with significant difference were found, and went upward or downward or disappeared after the stimulation of TCE with different dosages, which indicated that TCE induced the change of the proteomic expression in the liver cells. The mass spectrum identification and the IPI human database retrieval were used for identifying 9 proteins related to the L-02 Liver cells induced by TCE. CONCLUSION: The result provides an insight to TCE-related molecular mechanism and which might be useful for further study of the TCE-associated proteins and molecular markers.